As per
@jdrutten , drill holes in the SS arch and feed them through the SS tubing. Use grommets around the wire to avoid cutting them and then seal with your favorite sealant. Much of my outdoor wiring goes through the 1" dia. hand rails.
On that topic…
When you put wiring through stainless tubing, the grommets you want to (must use) are Heyco snap in bushings . These are nylon headed bushings which are available in every size under the sun in Back & white
Do not use rubber grommets. The sharp stainless will cut through them.
Drilling good round holes in stainless tubing is a little challenging. If you don’t do it the right way, they end up oval- shaped with lots of burrs.
Here are some pointers
Xmas tree bits are fabulous, as they open up a pilot hole to larger sizes keeping a perfect circle. You will need a short version that gets up to your diameter in few steps, as you’ll run out of depth
If you want to use regular drill bits, use tungsten carbide absolutely
Then there is a serious “trick”
To drill round holes in sheet steel, etc, put a piece of rag on the hole when you drill. In other words, you are drilling through the rag.
Do not ask me why this works. It just does.
And use cutting fluid. NOT wd forty
Good luck